, the thing is necessarily removed also;
in other words, that without which the thing, and which itself
without the thing, can neither be nor be conceived.

DEFINITION III. By idea, I mean the mental conception which is
formed by the mind as a thinking thing.

Explanation.--I say conception rather than perception, because
the word perception seems to imply that the mind is passive in
respect to the object; whereas conception seems to express an
activity of the mind.

DEFINITION IV. By an adequate idea, I mean an idea which, in so
far as it is considered in itself, without relation to the
object, has all the properties or intrinsic marks of a true idea.

Explanation.--I say intrinsic, in order to exclude that mark
which is extrinsic, namely, the agreement between the idea and
its object (ideatum).

DEFINITION V. Duration is the indefinite continuance of
existing.

Explanation.--I say indefinite, because it cannot be
determined through the existence itself of the existing thing, or
by its efficient cause, which necessarily gives the existence of
the thing, but does not take it away.

DEFINITION VI. Reality and perfection I use as synonymous terms.

DEFINITION VII. By particular things, I mean things which are
finite and have a conditioned existence; but if several
individual things concur in one action, so as to be all
simultaneously the effect of one cause, I consider them all, so
far, as one particular thing.

AXIOMS

I. The essence of man does not involve necessary existence, that
is, it may, in the order of nature, come to pass that this or
that man does or does not exist.

II. Man thinks.

III. Modes of thinking, such as love, desire, or any other of
the passions, do not take place, unless there be in the same
individual an idea of the thing loved, desired, &c. But the idea
can exist without the presence of any other mode of thinking.

IV. We perceive that a certain body is affected in many ways.

V. We feel and perceive no particular things, save bodies and
modes of thought.

N.B. The Postulates are given after the conclusion of Prop.
xiii.

PROPOSITIONS

PROP. I. Thought is an attribute of God, or God is a thinking
thing.

Proof.--Particular thoughts, or this and that thought, are
modes which, in a certain conditioned manner, express the nature
of God (Pt. i., Prop. xxv., Coroll.). God therefore possesses
the attribute (Pt. i., Def. v.) of which the concept is involved